Residual current protection devices are known, which monitor electrical lines that lead to a partial power supply system or load, and by the occurrence of a residual current, therefore a difference between the fed and derived current, disrupt the power supply of the partial power supply system. Normally, the electrical lines that lead to the partial power supply or load are monitored through a summation current transformer. Upon occurrence of a residual current, a trigger circuit connected with the summation current transformation is activated, which in turn separates switch contacts, through which the partial power supply or the load is separated from the supply network.
Such residual current protection switches have a setup to examine the functionality. Thus, a test line with a test button is designated, whereby the test line leads past parts of the current on the summation current transformer once the test button is activated. Upon activating the test button, a triggering of the residual current protection switch occurs, whereby the lead is separated from the supply network through this inspection. That is why this inspection is often not executed, because for example loads like computers or servers react sensitively to disruptions in the power supply, or due to the inconvenience of having to reset the clocks from different electronic devices, like video recorders, after a power interruption.
In order to hinder a disruption of the power supply to the load during the inspection, a switching device can be used to bridge over for the duration of the inspection of the residual current protection switch. Now the problem exists that by the bridging over of the residual current protection switch under real conditions there will by asymmetry in regards to the part of the current, which is guided through the switching device on the residual current protection switch before the bridge-over is complete or the residual current protection switch cannot be reset after inspection without triggering it.
In order to compensate for this asymmetry, the lines from the switching device can be coupled with each other for bridging through a transformer. Through this, there should be a symmetry of the two currents, which should be used to compensate for the asymmetry of the bridge over switch.
This theoretical function or effect, however, does not exist in the reality of an electrical installation environment. In real systems, actual asymmetry occurs that is so big that its compensation, in accordance with the state of technology, is only possible with very large magnetic cores. Nevertheless, this is disadvantageous in practice, because such magnetic cores have very large dimensions and mass, which makes their integration in a conventional installation difficult. Such cores consist of high quality materials and illustrate a significant cost factor from a corresponding switching device. Both the dimensions as well as the high costs of such practical switching devices decrease the processing, whereby often the installation of such switching devices is waived at a whole. This leads to the functionality of the residual current protection switches, which should protect load circles with an undesired switch off, not being inspected for a longer period of time and through this, a possibly defect residual current switch is also not recognized.
Through this, the security in electrical installation arrangements decreases, which exposes people to bodily harm and the systems to a constantly increasing hazard.